Apparatus for forming metal fibers



June 1963 H. T. FRANCIS APPARATUS FOR FORMING METAL FIBERS Filed July13, 1960 2 m I 7 m m m 5 I 6 1 R 7 n 474 4 W F w mwi a Ali m l M M v Q Hw y 2 2 m v are The present invention is directed to a method and apparatus for forming metal fibers and more particularly, to a method andmeans whereby very thin fibers of uniform dimension are readily andconveniently formed.

As employed in this specification and claim the term fibers denotes anelongated metallic filament having a long dimension substantiallygreater than its mean dimension in cross section; in other words,relatively elongated metallic bodies of fine cross section. As a generalrule, a fiber should have a length of at least times its mean dimensionin cross section. The term mean dimension is related to the shape of thefiber or filament in cross section and refers to the diameter in thecase of a circular filament, and in the case of a rectangular ribbon,denotes one-half the sum of the short side and the long side of therectangle.

Metal fibers are currently manufactured primarily by four differentmethods, namely; scraping from wire, machining in a lathe, cutting froma stacked sheet, and wire drawing. In all of these methods the fibersproduced are of relatively large cross section. That is, it is very.difiicult to produce extremely thin fibers. This is not to say that thelikelihood of manufacturing thin fibers, by the aforementionedtechniques, is entirely precluded. On the other hand, none of thesemethods, would continuously produce extremely thin (on the order of 0.5thousandth of an inch in cross section) fibers.

All of these are mechanical methods with resultant drawbacks.Furthermore, as will be readily understood, only limited control of thefiber dimension is possible with these methods. For example, scrapingfrom wire would allow the least control over fiber dimension.*Contrariwise, cutting from a stacked sheet will provide the bestaccuracy. The latter method though accurate, is costly in that amultiplicity of operations upon the raw material are necessary.

In contradistinction to the teachings and practices of the prior art, Ihave developed a primarily electrochemical method enabling continuousmanufacture of uniformly fine metal fibers and relatively uncomplexapparatus therefor.

it is accordingly, an object of the present invention to establish animproved method of forming thin metal fibers.

Another object of the present invention is to provide a method andapparatus for the continuous manufacture of extremely thin fibersexhibiting ease of control over fiber dimension.

Still another object of the instant invention is the provision of amethod, and apparatus therefor, of electroforming metal fibers.

Yet another object of the instant invention is to provide a method, andapparatus therefor, for the continuous manufacture of extremely thinmetal fibers.

The foregoing objects and others which will become apparent from adetailed reading of the description to follow, are accomplished bye-lectrodepositing metal from an appropriate bath onto circular rotatingdiscs immersed in the bath and controlling the dimensions of the fiberby regulating the current density in the solution and the rate ofrotation of said discs.

In the drawings:

FlGURE 1 is a schematic View, partly in section, of

atent isc apparatus capable of performing the method of the instantinvention.

FIGURE 2 is a schematic perspective View, partly in section,particularly useful in describing the application of the principles ofthe claimed invention.

FIGURE 3 is a perspective view of two discs illustrating an alternativeembodiment thereof.

FIGURE 4 is a view of a bisected conductive disc with a fiber 23electrodeposited thereon in accordance with the teachings of thiinvention.

Before describing my method in detail, it will be helpful to outline theutility of metal fibers. Because of the increasing concern over thestrength to weight ratio of metal structures and/or articles a needexists for increasing such ratio. Immediately, one recognizes that asubstantial weight reduction coupled with a small decrease in strengthwill result in a greatly improved structure. It has been discovered thata sintered interlaced network of metal fibers can, in many instances,provide adequate structural strength coupled with a material reductionin weight, and it is along these lines that fiber metallurgy has rapidlydeveloped. However, the ever increasing demands for metal fibers hasresulted in the need for a method for economically and efiicientlymanufacturing thin metal fibers.

For a more detailed description of metal fibers their field of use, thereaders attention is directed to copending applications, Serial Numbers492,007, filed March 3, 1955, and 6,290, filed February 2, 1960, bothassigned to the assignee of the present application.

Turning next to the drawings, FIGURE 1 shows a device for performing mymethod which includes a container 10 having mounted therein: rotatableshaft 16, anodes 15 and cylinder 11 comprising discs 12 and 13.Conductive metallic discs 12 are alternately interspersed betweennonconductive dielectric discs 13. Shaft 16 is insulated from containerill by means of bushings 24 and is opcratively connected to motor 20.Shaft 16 has a key 15a runing therealong which couples rotational motionfrom the shaft to discs 12 and 13. One end of shaft 16 is connected to apole of battery 21 while its other end is connected to the armature ofmotor 20.. That portion of shaft 16 connected to motor 20 is made of anon-conducting material 1612 in order that motor 20 be insulated frombattery 21. Anodes 15 are connected to the other pole of battery 21through switch 22. Anodes 15 are supported within, and insulated from,container 10 by rubber bushings 25. Switch 22 through its variouspositions, enables control of the voltage applied across shaft 16,conducting discs 12 and anodes 15. By this expedient the current.density in bath 19 is regulated.

Discs 12 are each provided with an opening 18 corresponding to the shaft16 and are made of a passive metal, for example, stainless steel. Bypassive metal is meant that type of materia to which anelectrodepositable coating will not adhere.

Bath 19, within container 10, is a solution containing the metal to bedeposited upon conducting dis-cs 12. The fiber composition is chosen bya proper selection of the constituents in bath 19. For example, bath 19may comprise solutions of: iron, nickel, copper, combinations thereof,or any other metal which is readily electrodepositable. When switch 22is moved from the off position to some positive potential, a current isestablished between the anodes 15 and conducting discs 12 causing metalions contained in the bath 19 to be deposited upon conducting discs 12.It is noted that no deposit is formed on discs 13 because they arenon-conductive.

It is noted that cylinder 11, when mounted on shaft 16, has a portionthereof (/1 see FIGURE 1) extending out of bath 19. The extent ofprotrusion of cylinder 11 3 out of bath '19 is not critical, however, itmust extend beyond bath :19 to enable removal of the formed fibers.

The thickness 1 (see FIGURE 4) of fiber 23 is governed by the angularvelocity of cylinder Ill and the magnitude of the current applied. Inother words, the thickness is dependent upon the time a finite area (forexample da in FIGURE 3) is in the bath and the magnitude of the currentdensity causing the metal in the solution to be deposited on said area.The width w of fiber 23 is independent of the above noted factors,however, w is controlled by providing sets of discs 12 having differentthicknesses.

In operation, the fiber thickness is predetermined by calculating therate of rotation of cylinder .11 for a given voltage setting of switch2.2;. After controls 20a and 22 are set and metal is being deposited, adoctor blade 14, supported by posts 14a (suspended out of bath 19 but incontact with cylinder '11) scrapes the fibers from discs 12 prior to there-entry of the disc surf-aces into bath 19.

The means for transporting the fibers from doctor blade 14 are not shownin that many well known devices are suitable therefor. A conveyor beltpassing immediately beneath the trailing edge of doctor blade 14-operates satisfactorily as the fiber transporting device.

FIGURE 3 depicts an alternative embodiment of the conducting discs 12whereby the fibers 23 are of finite length. This is brought about bycircumferentially spacing, about discs 12 nonconducting sections 17.Sections 17 are dielectric and may be of the same composition as discs13. Fiber metal will only deposit upon the conducting sections and,dependent upon the number and displacement of sections 17, specificlengths of metal fibers are produced. In all cases having nonconductivediscs 13 at both ends of cylinder 11 provides most efiicient operatonbecause then no metal is deposited on the exposed planar faces of thediscs.

My inventoin may best be fully envisioned by reference to the followingexamples:

Example I The production of nickel fibers according to my invention isaccomplished under the following bath conditions:

Bath composition:

Nickel sulfate, NiSO -7H O gr-ams/liter 300 Nickel chloride, NiCl -6I-IO do 60 -Boric acid, H BO do 38 Temperature C 54 pH 2.0

Cylinder Speed Current Den- Fiber Thickness (square feet per sity(amperes (thousandths of hour passing per square foot) an inch) throughbath) 4 Example II The same equipment produces iron fibers when an ironplating bath is used under the following conditions:

Bath composition: Ferrous ammonium sulfate,

Fe(NH (SO "grams/liter" 350 Temperature C Fiber thickness for irondeposition was found to be very similar to that for nickel, being about8% greater than the nickel thickness under like conditions of cylinderspeed and current.

Example III An example of alloy fiber production is brass, plated fromthe following bath and with the conditions noted:

Bath composition:

The plating efficiency of brass baths is quite variable, therefore, onlyan approximate fiber thickness is given; thicknesses generally of thesame order as for nickel are produced under similar conditions ofcylinder speed and current.

From the foregoing it will be appreciated that I have provided a novelmethod and apparatus for the production of uniformly fine fibers.However, it is noted that the invention is not limited thereto. Themethod affords considerable versatility coupled with the uniquecapability of enabling the continuous manufacture of metal fibers ofsmaller cross section than those heretofore presented.

Accordingly, it is to be understood that within the scope of theappended claim the invention may be practiced otherwise than has beenspecifically set out in the detailed description of my invention.

I claim as my invention:

In combination, apparatus for the manufacture of thin metal fiberscomprising: container means; a solution containing an electrodepositablematerial in said container, conductive means suspended within saidcontainer but insulated therefrom; a series of discs having conductiveand non-conductive sections uniformly spaced from each other about theperiphery of said discs; a series of nonconductive discs interspersedalternately between said last mentioned discs whereby all the discs arein axial alignment and substantially completely immersed in saidsolution; means for rotating said discs in unison; means for applying avoltage across said discs and the conductive means; means for removingthe electrodepositable material from said conductive sections; means forregulating the rate of rotation of said rotating means; and means forregulating the magnitude of voltage applied across said discs and theconductive means.

References Cited in the file of this patent UNITED STATES PATENTS1,600,257 Topping Sept. 2.], 1926 1,878,540 Reinhardt et al. Sept. 20,1932 FOREIGN PATENTS 3,160 Great Britain Feb. 11, 1909

